Presently, the heat dissipation in electronic control units, which have a relatively high power loss in comparison to the overall size, is generally controlled by the selection of the housing material. As a housing material, aluminum has advantageous properties with respect to the heat dissipation, but aluminum is more costly than plastic. If plastic is to be used as a housing material, it is usually necessary to significantly increase the overall size of the control unit, to achieve sufficient heat dissipation. In order that the heat may be dissipated from the control unit, good heat conduction is required between the control unit and the surroundings. However, plastic conducts heat poorly, so that the location of the heat input becomes relatively hot and the surfaces in the immediate proximity of the heat input exhibit only little heat dissipation. As a result, a simple enlargement of the housing surface does not always bring about an improvement with respect to the heat dissipation.
If the thermal connection of the heat source to the housing may be provided over a large area, then a plastic housing may also dissipate sufficient heat. This may be achieved, for example, in that the heat source is connected to a heat spreader, for example, an aluminum plate, and the heat spreader is connected over a large area to the housing. It is disadvantageous in this case that a separate heat spreader is necessary and has to be introduced into the housing in an additional work step.
German Patent Application No. DE 20 2009 000 615 U1 describes a power semiconductor element potted in molding compound, in which a power semiconductor including metallic contacts, which are led to the outer side of a mold module, is enclosed in enveloping injection using thermosetting plastics, and a heat conduction section through the semiconductor and a substrate carrier is provided for heat dissipation of a bottom side, a contact tab, which is formed covering the surface of the contacts, is attached in the area of one of the contacts of the semiconductor on its upper side, and a heat-conducting element is provided on the planar section of the contact tab in a way which conducts heat to the upper side of the mold module, to form a second heat-conductive bridge on the outer side of the module.